Monument Rocks — rock formation
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Monument Rocks

  • 2 min read
  • 38.791° N 100.762° W

Interesting facts

  • The chalk belongs to the Smoky Hill Chalk, part of the Niobrara Formation laid down roughly 87 to 82 million years ago.
  • The chalk is built from coccoliths, the microscopic plates of plankton that drifted down onto the floor of the inland sea.
  • The Smoky Hill Chalk is a fossil Lagerstätte, famous for exceptionally preserved mosasaurs, plesiosaurs, the flying reptile Pteranodon and the toothed diving bird Hesperornis.
  • George F. Sternberg found a giant fish, Xiphactinus, in this chalk with an entire smaller fish, Gillicus, preserved inside its body.
  • The fossil beds of the Kansas chalk were first explored by a Yale expedition led by Othniel Charles Marsh in 1870.
  • The rocks stand about 802 m (2,630 ft) above sea level, on the high plains near the Smoky Hill River.

Why it is worth it

Monument Rocks rise out of the flat shortgrass prairie of western Kansas like the ruins of a pale stone city: a cluster of chalk buttes, walls and arches up to about 70 ft (21 m) high, standing alone above the fields of Gove County. They are also known as the Chalk Pyramids, and their best-known feature is the Keyhole, an arch pierced through one of the walls; local lore holds that the opening began as a bullet hole many years ago and slowly widened.

The chalk is the floor of a vanished ocean. Around 80 million years ago, in the Cretaceous period, the Western Interior Seaway divided North America in two, stretching from the present Gulf of Mexico north through Canada, and the shells of countless microscopic organisms settled on its bed as soft limy ooze. The Smoky Hill River, rain and wind have since stripped away the surrounding rock and left these remnants standing. The Kansas chalk is famous for its marine fossils — fish, turtles, oysters, sharks' teeth, birds and the great swimming reptiles that hunted in the seaway — many of which can be seen in museums of the region.

The rocks were a landmark long before they were a sight. Explorers on John C. Frémont's expeditions noted them in the 1840s, and in the 1860s the Smoky Hill Trail to the Colorado goldfields passed nearby. In 1865 the Butterfield Overland Despatch began running stages along the route, and Fort Monument was established the same year to protect travellers. In 1968 Monument Rocks became the first site in Kansas to be designated a National Natural Landmark by the U.S. Department of the Interior, and in 2008 they were named, jointly with Castle Rock some 31 miles to the east, one of the 8 Wonders of Kansas. The formations stand on private land whose owners allow the public to visit.

Getting there

Monument Rocks lie about 25 miles south of Oakley and Interstate 70. From US Route 83, a signed county road leads east and south to the formations from a point just north of the Smoky Hill River crossing, about 25 miles north of Scott City. Garden City is about 91 km away in a straight line, and Garden City Regional Airport (GCK) about 96 km.

On these lists

The Most Beautiful Places in the United States 228The Most Remarkable Rock Formations in the United States 18The Most Beautiful Natural Wonders in the United States 68The Most Remarkable Rock Formations 107The Most Beautiful Natural Wonders 580

From the encyclopaedia

Monument Rocks are a series of large chalk formations in Gove County, Kansas, rich in fossils. The formations were the first landmark in Kansas chosen by the U.S. Department of the Interior as a National Natural Landmark. The chalk formations reach a height of up to 70 ft (21 m) and include formations such as buttes and arches. The carbonate deposits were laid down during the Cretaceous Period in what was then the Western Interior Seaway, which split the continent of North America into two landmasses. They are estimated to have been formed 80 million years ago.

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38.79060, -100.76200per Wikidata